Sulfuric acid–amine nucleation in urban Beijing

Abstract

Abstract. New particle formation (NPF) is one of the major sources of atmospheric ultrafine particles. Due to the high aerosol and trace gas concentrations, the mechanism and governing factors for NPF in the polluted atmospheric boundary layer may be quite different from those in clean environments, which is however less understood. Herein, based on long-term atmospheric measurements from January 2018 to March 2019 in Beijing, the nucleation mechanism and the influences of H2SO4 concentration, amine concentrations, and aerosol concentration on NPF are quantified. The collision of H2SO4–amine clusters is found to be the dominating mechanism to initialize NPF in urban Beijing. The coagulation scavenging due to the high aerosol concentration is a governing factor as it limits the concentration of H2SO4–amine clusters and new particle formation rates. The formation of H2SO4–amine clusters in Beijing is sometimes limited by low amine concentrations. Summarizing the synergistic effects of H2SO4 concentration, amine concentrations, and aerosol concentration, we elucidate the governing factors for H2SO4–amine nucleation for various conditions.

The driving factors of new particle formation and growth in the polluted boundary layer

“…The CLOUD measurements of NPF at 278 K with H 2 SO 4 , 1-2 ppbv ammonia and organics compare well with atmospheric observations in several polluted environments during cold seasons (Beijing winter; Jayaratne et al, 2017) and Yangtze River Delta region (Dai et al, 2017) implying low amine concentrations (< 4 pptv) in these regions in winter. Atmospheric observations in warm environments lie well above the J vs. GR line for 1 to 2 ppbv ammonia nucleating with H 2 SO 4 at 293 K. Ammonia concentrations of ∼ 10 ppbv could explain the observations from Madrid (Carnerero et al, 2018), Po Valley (Kontkanen et al, 2017) and Tecamac (Kuang et al, 2008), while unrealistically high ammonia concentrations (> 100 ppbv) would be needed to explain Beijing spring (Cai et al, 2017) or Nanjing summer (Yu et al, 2016). Therefore, NPF in the latter two cases is likely due to amines at pptv levels, which would match the CLOUD measurements well (magenta squares in Fig.…”

“…The loss rates of newly formed particles are approximated by the condensation sink of sulfuric acid to particles larger than 6 nm (x axis). Also shown are typical CS from observations in the polluted boundary layer at the following locations: Po Valley regional (San Pietro Capofiume, SPC) (Kontkanen et al, 2017), Madrid (Carnerero et al, 2018), Tecamac (Kuang et al, 2010), Nanjing (Yu et al, 2016) and Beijing (clean, transition and haze) (Cai et al, 2017). Dashed lines are calculated survival probabilities of 2.5 nm particles with growth rates of 2, 5 and 10 nm h −1 .…”

“…H 2 SO 4 nucleation at the kinetic limit is indicated by the cyan dashed line. Also shown are the mean values for sub-3 nm GR and sub-2 nm J from observations in the polluted boundary layer at the following locations: Shanghai (SH) (Yao et al, 2018), Beijing spring and winter (BJ) (Cai et al, 2017;Jayaratne et al, 2017), Madrid (urban: MAD and suburban: MAJ) (Carnerero et al, 2018), Po Valley regional (San Pietro Capofiume, SPC) (Kontkanen et al, 2017), Nanjing summer and winter (NJ) (Yu et al, 2016), Yangtze River Delta regional (YRD) (Dai et al, 2017), and Tecamac (TEC) (Kuang et al, 2008). The text colours indicate < 288 K (green), > 288 K (orange) or all year (grey).…”

Condensation sink of atmospheric vapors: the effect of vapor properties and the resulting uncertainties

“…We used the kinetic model presented by Cai et al 47 The losses of sulfuric acid monomers due to condensation are determined as L CS = C SA (CS SA (1 − η ) + CS 1SA+DMA η ) where C SA is the total concentration of sulfuric acid monomers, CS SA is the CS of sulfuric acid molecules while CS 1SA+1DMA is the CS of a cluster consisting of sulfuric acid molecules and DMA molecules. η is the ratio of sulfuric acid clusters of one sulfuric acid molecule and one base molecule to pure sulfuric acid molecules.…”

Supplementary material to "A Sulfuric Acid Nucleation Potential Model for the Atmosphere"

“…Additionally, wall loss rates are replaced with a coagulation loss rates to pre-existing particles. The coagulation loss rate was calculated from the Fuch's surface area (Kuang et al, 2010) during the various field campaigns and was assumed to be constant over the course of the nucleation events (Sihto et al, 2006;Iida et al, 2008;McMurry and Eisele, 2005;Cai et al, 2021;Eisele et al, 2006).…”